WASHINGTON — The Obama administration’s power to regulate greenhouse gases faces an important test Monday, when the U.S. Supreme Court hears arguments in a series of cases seeking to limit the reach of the Clean Air Act.

The cases challenge the Environmental Protection Agency’s relatively new authority to tackle climate change by regulating the emission of greenhouse gases, such as carbon dioxide. Scientists have established that those gases have made the planet warmer and its climate dangerously unstable.

The state of Texas and a small army of other petitioners — the case is six similar suits rolled into one — seek to stop the EPA from regulating the emission of carbon dioxide and similar gases from power plants and other facilities.

For now the EPA says only large facilities emit enough carbon dioxide annually to fall under the new regulations. Fewer than 400 Texas facilities and only a handful in the Dallas area currently emit more than 75,000 tons of carbon dioxide annually. But Texas Attorney General Greg Abbott and others argue that the EPA will eventually expand that threshold to include millions of facilities across the country — from hospitals to schools to large homes.

“The burden would be on everybody,” said C. Boyden Gray, a former ambassador to the European Union under President George W. Bush and White House counsel to his father.

“Whether a hospital wants to add a wing on or a plant wants to add an assembly line. They’d all need to go through a hearing for a permit. … This kind of pre-approval process would drive the country not to a halt, but create an enormous mess. That’s what is at stake.”

Environmentalists say the EPA is trying to rein in the scope of its new rules to avoid affecting medium or small facilities. They also argue that if the court dials back the EPA’s authority, the nation will be handicapped in its efforts to confront its most serious environmental challenge.

“These regulations are aimed at controlling the most threatening form of pollution we have ever faced under the Clean Air Act,” said Sean Donahue, an attorney for environmental groups who have been allowed to join the case on the side of the EPA.

Weakening the EPA’s ability to control those kinds of emissions, Donahue said, would be foolish.

So what’s the case about?

The EPA says that because it has authority to regulate greenhouse gases emitted from vehicles, it automatically has power to regulate them from stationary sources like power plants and, if critics’ worst-case scenarios come true, millions of other buildings.

The case began in one sense early in the Bush administration. In 2003, the EPA announced it would not regulate emissions of greenhouse gases from cars and trucks because the gases weren’t “air pollutants” under the law. Even if they were, the EPA leadership decided, evidence linking them to global warming was uncertain.

Several states and environmental groups sued to force the agency to fulfill its duties under the act, and in 2007 the Supreme Court ruled 5-4 that they were right. The “overwhelming consensus” of science had shown that greenhouse gases posed a threat to the planet, wrote then-Justice John Paul Stevens. Greenhouse gases, the court ruled, were pollutants and the administration was required to take action.

New standards took a few years, but in 2010 the EPA, by then under a new president, announced standards for car and light truck manufacturers. Last week, President Barack Obama announced that new rules for heavy trucks are coming, too.

But carbon dioxide is different than pollutants previously covered by the Clean Air Act, like those that cause smog. The law sets thresholds for how much of a pollutant a facility can emit before it must be permitted. Those limits were designed with other pollutants in mind, and have limits so low that, as the EPA acknowledged, an “absurd” number — millions — of facilities would need permits.

To avoid that, EPA said it would tailor the new rules to only target facilities that emit the annual equivalent of either 75,000 or 100,000 tons of carbon dioxide, depending on the plant. An EPA spokesperson said over the weekend that permits would be required every five years, or when expansions boost their emissions above the thresholds.

But industry voices and the states that have sued point out that the EPA’s “tailoring” of the new standards is only temporary. Unless the law is changed, eventually all those other millions of facilities would be brought under the regulations, they say.

“EPA promises to find ways to ‘streamline’ permitting,” attorneys for the energy-intensive manufacturers work group wrote in a brief in one of the cases that has been combined for Monday’s arguments. “Its goal — and commitment — is to regulate as many as possible of the minor emitters, as rapidly as possible.”

The full cost to businesses of complying with the new regulations won’t be known until the program is more fully developed. But representatives of Texas’ largest companies see the case before the justices Monday as a critical opportunity to check what they see as a flawed response to exaggerated concerns about climate change.

“It’s not whether greenhouse gases are dangerous or not or if they are leading to global warming,” said Stephen Minick, vice president at the Texas Association of Business. “The question is whether the Clean Air Act as passed by Congress is a rational tool to address climate change.”

Beyond legal questions, he said, the case is about the science of global warming and how policymakers choose to confront it.

The government, he said, can’t say exactly how much U.S. carbon emissions have affected global warming. As a result, it can’t measure how much good its new regulations will do. Asking workers and businesses to absorb certain costs now for uncertain benefits in the future isn’t fair, he said.

“The negative financial impact on people on the short-term is going to be far more damaging to them than any changes in the climate we will see, even if the scientific consensus is right,” he said. “The government wants to fix this by taking money out of the pockets of millions of people, many of whom cannot afford it.”

It’s very unlikely that the suit, even if plaintiffs win, would stop entirely the regulation of greenhouse gases from industry. Last year, the president announced new rules for newly constructed power plants, and he’s expected to announce more far-reaching rules for existing plants sometime later this year.

Industry voices in Texas, especially those related to energy production, have decried both sets of the rules, and Texas lawmakers such as Sens. John Cornyn and Ted Cruz and Rep. Ralph Hall have said they will be among the most costly in history.

But those rules are not directly being targeted by the cases being heard Monday — unless, that is, a long-shot argument by Abbott persuades the justices to overturn their 2007 decision altogether.

Abbott brought the case Texas vs. EPA, one of those that were combined for arguments Monday. In it, he argues that the court wrongly concluded greenhouses gases should be considered “air pollutants” under the Clean Air Act.

Texas isn’t the lead plaintiff in Monday’s case, and Abbott won’t be arguing before the justices. But the brief filed by his office for the case will be considered by the justices when they decide the case, probably later this year.

Gray, who was an energy ambassador for George W. Bush and helped chair review of environmental regulations for President Ronald Reagan, said Thursday that he expects Abbott’s continued pressing for overturning the 2007 decision to have “no impact” on the justices.

But Donahue, who also thinks it’s unlikely the court will reverse itself, said Texas carries enough clout as a party in the case that Abbott’s arguments will be considered.

“Any time you have a state as a litigant in a case like this, the court is going to give it very close consideration,” he said.

But as the legal arguments have been refined again and again over months of hearings and lower court decisions, he added, Abbott’s position has won little support. “So far, he has no success in making that argument.”

Abbott’s office didn’t respond to a request for comment.

Even though he feel it’s a long-shot legal bet, Gray said there is some value in having a party like Texas make the most aggressive argument, challenging even the already settled law involving climate change.

“There is some use in having that argument made in the brief, reminding the court that that is a still very important topic,” he said.

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